Tomato psyllid
A tiny jumping sap-sucker that causes yellow, purple-tinged, upward-curling leaves on tomatoes, peppers and potatoes and can spread a bacterial disease.
Also known as: Potato psyllid, Bactericera cockerelli
Symptoms and identification
Leaf edges yellow and curl upward, and new growth may turn purple or stay small and clustered. Flowers drop and fruit are small and poor. Sticky honeydew and a white sugary crust cover leaves, and tiny flat orange nymphs can be seen on leaf undersides. Potatoes may have striped, brown flesh when fried (zebra chip).
Causes
Adults fly in from wild hosts and weeds in spring and early summer and lay tiny eggs on leaf edges. Feeding injects a toxin and can carry a bacterium that causes zebra chip disease in potatoes.
Organic treatment
Spray insecticidal soap, horticultural oil or neem oil on leaf undersides, repeating every 5 to 7 days. Dusting with sulphur may reduce numbers where it is allowed for the crop.
Prevention
Use fine insect mesh on young plants, remove weeds, particularly those in the nightshade family, and inspect leaf undersides weekly. Use yellow sticky traps to detect adults.
Chemical treatment (use with care)
Use an insecticide labelled for psyllids on that crop, following the label and harvest wait.